RIYADH- Marriott International will invest $2 billion in Saudi Arabia in the next four years by almost doubling the number of hotel rooms it operates there, an executive said on Monday.

The kingdom aims to boost domestic and international tourism in its drive to diversify the economy away from oil exports. It is has set a target of $46.6 billion in spending by local and foreign tourists in 2020, up from $27.9 billion in 2015.

Alex Kyriakidis, Marriott's president and managing director for the Middle East and Africa, told Reuters his firm would expand the number of rooms at its hotels to about 12,500 in the next four years from almost 6,800 now.

Building now underway on the almost 6,000 new rooms would cost $2 billion, he said in an interview, adding the company would operate 52 hotels once work was completed, up from 23 now.

The company operates the Marriott, Ritz Carlton, Le Meridien and Sheraton brands in Saudi Arabia, among others.

Riyadh's Ritz-Carlton Hotel reopened this month, more than three months after it was converted into a temporary prison for members of Saudi Arabia's business and political elite detained in an anti-corruption purge. 

He said Ritz Carlton's temporary closure did not hurt the group's operations in the kingdom, adding that the crackdown on corruption should reassure investors.

He said domestic tourism still accounted for most visitors.

The Saudi authorities have said they would issue tourist visas to foreigners this year, but details have not been disclosed.

To attract visitors, Saudi Arabia said it would develop resorts on some 50 islands off the Red Sea coast and an entertainment city south of Riyadh featuring golf courses, car racing tracks and a theme park.

(Writing by Stephen Kalin; Editing by Saeed Azhar and Edmund Blair) ((stephen.kalin@tr.com; +971 52 322 9759; Reuters Messaging: stephen.kalin.thomsonreuters.com@reuters.net))